Porencephaly is a congenital disorder in which a cyst or cavity communicating with the cerebral ventricle is found in the cerebral hemisphere (Non-patent Document 1), and assumed to be caused by a disturbance of vascular supply such as infarction or hemorrhage during the fetal period (Non-patent Documents 2 and 3). Clinically, porencephaly causes hemiplegia (most often), quadriplegia, epilepsy, and intellectual disability (Non-patent Documents 4 and 5). Delivery of monozygous twins, cardiac arrest or abdominal trauma of the mother, a deficient protein C anticoagulant pathway, and cytomegalovirus infection are risk factors for sporadic porencephaly (Non-patent Documents 2 and 6).
In recent years, mutations in the gene encoding the α1 chain of type IV collagen (COL4A1, MIM 120130) were reported to be responsible for familial porencephaly (Non-patent Document 7). After that, de novo mutations in the COL4A1 gene were also reported in a sporadic case (Non-patent Documents 8 to 10), confirming involvement of abnormality of the COL4A1 gene in both sporadic and familial porencephalies. However, there still remain many cases in which no mutation in the COL4A1 gene can be identified.